Lens material for reducing effective color vision

ABSTRACT

A spectacle lens is provided for a person with deficient color vision, the lens having a support with a transparent mosaic on the support constituted by a plurality of juxtaposed small color filter regions of different colors and respective spectral transmission factors which differ in magnitude in inverse proportion to the diagnosed sensitivity of the intended user.

I v UllltEd States Patent 1 1 1 1 3,731,993 Piringer 51 May 8, 1973 [54] LENS MATERIAL FOR REDUCING [56] References Cited EFFECTIVE COLOR V N FOREIGN PATENTS OR APPLICATIONS A P" V' [75] Inventor i i 59,782 11/1891 Gennany ..351/l63 437,739 11/1926 Germany 73 Assigneez National Patent Development Cob 744,324 7/1944 Germany ..35l/165 poration, New York, NY. Primary ExaminerDavid Schonberg [22] F'led: 1971 Assistant Examiner-Robert L. Sherman [21] A l. No 197,092 Att0rney-Waters, Roditi, Schwartz & Nissen Related U.S. Application Data [57] ABSTRACT [63] Continuation of Ser. No. 866,293, Oct. 14, 1969, A Spectacle lens is provided for a person with abandoned cient color vision, the lens having a support with a transparent mosaic on the support constituted by a [52] U.S. Cl. ..35l/165,117/33.3 351/44 plurality of uxtaposed small color fllter regions of d1f- 7/10 843d ferent colors and respective spectral transmission factors which differ in magnitude in inverse proportion to the diagnosed sensitivity of the intended user.

6 Claims, 6 Drawing Figures PATENTED HAY 8 I975 SHEET 1 OF 3 PATENTEUHAY' 8m SHEET 2 0r 3 Z 0006 mm b); 21,0 mm 4:

FIG. 2.

SHEET 3 [IF 3 FIG. 4

FIG.

FIG-6 LENS MATERIAL FOR REDUCING EFFECTIVE COLOR VISION CROSS RELATED APPLICATION vides improvement in color vision; to its production;

and to its use. The invention also extends to articles embodying it.

It is an object of the invention to provide an improved lens material which is useful to assist vision; either in providing compensation for defective perception of colors to give a more normal effect or possibly by modifying the light transmitted to a normal eye to give a desired visual effect.

It is a particular, although not exclusive, object of the invention to provide a lens material which is useful in assisting defective color vision.

Difficulty in distinguishing normally between certain colors, ordinarily described somewhat misleadingly as color-blindness, is regarded as arising from a low sensitivity to one of the primary colors, blue, green or red. The colors commonly concerned and confused, are red and green, a person with a low-sensitivity to red being described as a protanope and one with a low sensitivity to green being described as a deuteranope.

These deficiencies are currently deemed incurable from a medical point of view, and there are no means on the market today by which a person suffering from defective color vision can alleviate his affliction in a simple and practical manner such as, for example, in the way myopia or astigmatism can be relieved by the use of spectacles with appropriate compensating lenses.

German Patent No. 59,872 (Kamptz) published in" 1891 described eyeglasses for color blind people. Therein was disclosed a round spectacle glass with a plane surface on one side, the other side being ground with slight inclinations to form two facets (similar to a roof) or three, four or six facets (similar to a pyramid of small height), thereby forming sectors whose surfaces were inclined in different directions. Each facet caused a slight deviation of the light rays, and when a single object was observed through such a spectacle glass a number of equal images appeared simultaneously; for example a plurality of images of the same object were seen arranged in a circle. Cut pieces of colored glass, each in the form of its sector, were arranged between the planar rear surface of the faceted spectacle glass and the eye. The colors employed were red, violet, blue, green, yellow and orange and no colors were repeated, each color existing in one sector only. When observing an object, a number of differently colored images appeared simultaneously.

ln 1953 a proposed arrangement was made in which persons with color deficiencies would wear glasses with three horizontal stripes in red, green and colorless.

Both of the above arrangements require that the user compare consciously i.e. make several comparisons of separated pictures (seen through large color filters) and draw conclusions according to the relative lightness of the colors of said pictures, to obtain finally a personal judgement concerning the colors presented.

None of these proposals were ever put into use and heretofore no device is known which can alleviate deficient color vision in a practical way with just a single picture m view.

It is an object of the invention to restore the proper ratio of the excitations for red, green and blue as well as possible.

During an ordinary viewing operation, the rays of light incident on the eye cause certain excitations for red, green and blue in the retina. The color perceived depends on the ratio of the excitations for red, green and blue and on their relative intensities. A low-sensitivity for red or green changes the proper ratio of the three excitations. As a result there is an incorrect ratio, which is one cause for color deficiencies. Such persons require, for example, five times as much red, or twice as much green to obtain a perception comparable to a normal eye.

For the restoration of the proper ratio of the three excitations, it would be necessary to touch the relatively low-sensitive red keys in the eye of a color deficient person as strongly as possible, and to touch the high-sensitive blue keys only weakly. In the most common case, the green keys have to be touched" with medium intensity. In this case, the resulting perception effect would be as if all three keys were touched in about the same strength.

The human apparatus of vision (eye and brain) has the ability to adjust to abnormal light conditions such as occur when a color filter is placed in front of the eye. The initial effect is to perceive an increased sensation of the color of the filter, but in time the visual system compensates for the excess light of the particular color and the viewer starts to see objects with the same relative colors to which he was used to seeing them so that the filter is effectively overcome in respect of the filter color. The response of the human apparatus of vision (eye and brain) to each excitation immediately commences with an adaptation consisting of an increase of the sensitivity for the complementary color. In order to utilize such increases of sensitivity, the excitations have to change more rapidly, preferably in an automatic manner. Thus, for example, an eye with a low green sensitivity is advantageously preconditioned at the instant it looks through a red filter immediately before switching to a green filter whereupon any green light coming from a green object is noted with greater emphasis.

The requirement for an automatic change is met by a property of the function of the eye. Mainly, each eye remains at rest for a very short time only, and is in steady movement. Slow glance movements have a duration of 0.1 to 0.2 seconds, whereas rapid glance movements take only 0.02 to 0.06 seconds. Even when fixing at a point, the eye steadily carries out minimal movements, and these seem to be absolutely necessary for transmitting the excitations. Experiments with artificially stabilized eyes have shown that in this case the image fades, and suddenly nothing can be seen with the open eyes, until the eye is freed from its artificial stabilization and can resume its natural movements.

The present invention contemplates a lens material comprising a transparent mosaic including a plurality of juxtaposed small color filter regions of different colors, each of said different colors being arranged repeatedly to provide a substantially uniform distribution of said filter regions of each of the different colors throughout said mosaic.

The colors of the color filter regions are primary colors. Said color filter regions are hexagonal and are arranged so that no two regions of the same color are adjacent.

The invention extends to spectacle lenses made of the aforesaid material and to spectacles incorporating such lenses. A spectacle lens for a person with deficient color vision comprises a support, and a lens material on said support comprising a transparent mosaic including a plurality of juxtaposed small color filter regions of different colors adapted to compensate for the deficient color vision of the wearer, said regions being arranged in repeating groups to provide a substantially uniform distribution of said filter regions throughout said mosaic. Said color filter regions have respective spectral transmission factors which differ in magnitude in inverse proportion to the diagnosed sensitivity of the intended user to the primary colors (red, green and blue).

The support of said spectacle lens is a clear lens element and said mosaic may be a photographic diapositive mounted on said lens element on the side thereof closest to the wearer.

In a more specific embodiment the support is a clear lens element and said mosaic is a photographic composition on said lens element.

Another aspect of the invention comprises a method of making a transparent mosaic by projecting an over size image of said mosaic onto a screen, photographing said image on color film with reduction in size, and securing the film onto a clear lens element.

To produce a mosaic of the three primary colors, an image for each color can be projected from a separate projector, the three colors being projected simultaneously with different intensities. Each of the projectors can project through an appropriate color filter and a diapositive having opaque areas corresponding to the parts of the mosaic that are not to be formed in the particular color.

Some embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 represents a mosaic lens material subdivided into hexagons in three different colours, in 550-fold linear enlargement;

FIG. 2 represents an enlarged central section through a schematic eye;

FIG. 3 represents, in central section, the schematic eye and an eyeglass lens with the lens material of FIG. 1; and

FIGS. 4 to 6 show schematically the effect of individual color-filter elements u on the hexagonal cones ofthe retina; in 750-fold linear enlargement.

Referenced in the drawing are the transparent mosaic l, the eyeglass lens 2, the retina 3 in the schematic eye 4. Red color-filter elements are referenced as r, blue ones as b and green ones as ,g."

As can be seen in FIG. 1, the small color-filter regions form a mosaic consisting of hexagonal regions. Each individual color-filter region has a width of approximately 0.02 mm. This corresponds to a resolution of 50 lines per mm. The hexagonal-grid screen offers advantages over triangular or square grids, which are both feasible, in that it can provide three hexagons of different colors in symmetrical arrangement in every direction. Due to the minute size of the color-filter regions, the smallest possible eye movement suffices for moving into a field of a different color. The hexagons are arranged to border on each other with their vertical sides, because the most rapid eye movements occur in horizontal direction.

In FIG. 2 the conditions along a central section through the schematic eye are represented. The smallest angle of vision 6* amounts to approximately one minute of arc. The size of the smallest discernible dispersion disclet z* is indicated with a diameter of 0.006 mm. Two light rays incident at any smaller angle can only excite one single cone. Thus, the limit of resolution in the eye is defined.

In FIG. 3 the lens material in the form of mosaic 1 is secured on the eyeglass lens 2 and filters the light rays, which impinge upon the retina 3 in the interior of the eye 4.

Referring to FIGS. 4, 5 and 6, they schematically show the effect caused by three color filter regions of the mosaic in a small area of a schematic retina with hexagonal cones. The non-excited cones are represented in black, the excited cones by small hexagons. The drawing shows a place in the fovea centralis of the retina where the cones stand closely to each other. Outside of the fovea, the cones are no longer arranged so densely, because between them are located the color-insensitive rods (which can only distinguish between light and dark and serve for nocturnal vision). The transmission of light of the red filters is assumed to be 40 percent, that of the green filters 20 percent, and that of the blue filters 10 percent. The image observed by the eye is a small horizontal red line on a green background.

Thus, at the same place in the retina, the following excitation situations develop in rapid succession:

FIG. 4: 40 percent red transmitted to three horizontal tiers of cones. Above and below 0 percent (because the red filter absorbs green). Those places not hit by any light increase their sensitivity automatically.

FIG. 5: 20 percent green transmitted to the previously not lighted locations above and below. This light, impinging shockwise, is felt with greater than normal intensity. Simultaneously the area previously lighted with strong red light now receives approximately 0 percent (the green filter absorbs red).

FIG. 6: 10 percent blue (a theoretical value of maximum permeability however, the red line and the green background practically do not emit any shortwave radiation), i.e., effectively 0 percent blue and no corresponding blue excitation. Both the zones previously lighted with red, or green respectively, increase their sensitivity.

The gaze vacillates in opposed directions the action of FIG. 5 occurs, then the action of FIG. 4, then again FIG. 5, FIG. 6, FIG. 5 and so on repeatedly whereby the excitation changes suddenly and automatically because the eyeglasses are stationary, while the eye always moves.

The transition from one color-filter to the adjacent one occurs through the following voluntary and involunta y eye movements:

1. by fine-sweep shuttle-trembling of the eye in apparent rest position;

2. by movements of both eyes relative to each other in focussing;

3. by horizontal glancing movements, which often occur involuntarily;

4. by conscious glancing movements made voluntarily in various directions;

5. by head movements while viewing an object.

Hereby the observer steadily looks through many color filter regions. Hence, the cones of the retina uninterruptedly obtain light which is filtered in different colors. These steady filtering with certain chosen intensities causing a correction is exactly what is sought by the invention, e.g. the cones can receive a larger amount of red light and a smaller amount of blue light than under normal conditions without spectacles. In another embodiment, instead of red, green can be emphasized. The intensities for red, green and blue filter regions can be chosen individually and produced according to the invention.

A realization of the invention can be executed photo graphically by means of color film. The resolution of the film gives an estimate of the possible reduction in size. Current resolution lies at about 50 lines per millimeter. Hence a lower limit for the width of the color filter regions is approximately 0.02 mm. Its upper limit is about 1 mm and more. The optimal working size of the color filter regions depends on the individual extent of the color vision defeciency.

The following is a description of a method which has been found reasonably satisfactory for producing lens material. Three diapositive slides are prepared to serve as individual screens in three color projectors. These are made by photographing an image of the size of the image produced by the projectors and from angles corresponding to the three projection angles. The image is formed for each screen to comprise a pattern of two black hexagons and a clear one corresponding to the color'to be projected.

The finished diapositives are then, in each case together with a corresponding color filter, mounted and framed as slides ready for projection in each of the three projectors with the emulsion side towards the projection objective and not covered on that side. It is recommended to use as film material for these slides an extremely hard repro-film, orthochromatic, with a thick polyester-based carrier, on account of the desired dimensional precision.

The three projectors are placed in position, at the same angles used in taking the diapositives. Each projector is equipped with one of the three diapositives (with its mounted filter) and the images from the three projectors are adjusted precisely to form a three-colorgrid projection image on a screen. The screen can either be opaque white and the grid photographed by reflected light on the same side as the projectors, or transparent and photographed from the opposite side.

The latter technique avoids the risk that the beams from the three projectors mark themselves in the traversed air by the reflection of light from floating dust particles and affect photographs taken through these projection zones.

It is also necessary to adjust the individual intensities according to the inverse proportion of the diagnosed sensitivity of the intended user to the primary colors. Adjustment by reducing the current supplied to the projection lamps is ruled out because this would change the spectral composition of the projection light. There is the possibility of using supplemental neutralgrey filters, but the use of an adjustable iris-type diaphragm for each projector is preferred.

Once the desired light intensities have been adjusted for the three projectors, normal exposure can be effected. The development of the color film also takes place in the usual manner. The completed color-film is bonded to the inside of an eyeglass lens with the emulsion side turned towards the eye. The bonding can be achieved by the use of double-sided pressure-sensitive adhesive foil around the rims.

Preferably, the photographic lens of the camera is corrected for the dominant wavelengths of the filter colors and their focus differences should be adapted to the individual depth of the three color-emulsion layers, so that the minimal dispersion circle diameter can be attained for each layer including the bottom layer. It is found that the surface of an eyeglass lens according to the invention does not show any significant structure to the naked eye, but rather gives the impression of transparency with a slight colored veil.

The invention is not to be understood to be limited to correction of defective color vision. It is probable that the selectivity it provides will be of value in providing glare protection and in other ways.

Neither is the invention to be understood to be limited to a photographic mosaic: it could also extend to a mechanically constructed mosaic.

What is claimed is:

l. A lens material comprising a transparent mosaic including a plurality of juxtaposed small color filter regions of different colors, each of said different colors being arranged repeatedly to provide a substantially uniform distribution of said filter regions of each of the different colors throughout said mosaic.

2. A lens material as claimed in claim ll, wherein the colors of the color filter regions are primary colors.

3. lens material as claimed in claim ll, wherein said color filter regions are hexagonal and are arranged so that no two regions of the same color are adjacent.

4. A spectacle lens for a person with deficient color vision, said lens comprising a support, and a lens material on said support comprising a transparent mosaic including'a plurality of juxtaposed small color filter regions of different colors adapted to compensate for the deficient color vision of the wearer, said regions being arranged in repeating groups to provide a substantially uniform distribution of said filter regions throughout said mosaic, said color filter regions having respective spectral transmission factors which differ in magnitude in inverse proportion to the diagnosed sensitivity of the intended user to the primary colors, red, green and blue.

5. A spectacle lens as claimed in claim 4, wherein said support is a clear lens element and said mosaic is a photographic diapositive mounted on said lens element on the side thereof closes to the wearer.

6. A spectacle lens as claimed in claim 4, wherein said support is a clear lens element and said mosaic is a photographic composition on said lens element. 

1. A lens material comprising a transparent mosaic including a plurality of juxtaposed small color filter regions of different colors, each of said different colors being arranged repeatedly to provide a substantially uniform distribution of said filter regions of each of the different colors throughout said mosaic.
 2. A lens material as claimed in claim 1, wherein the colors of the color filter regions are primary colors.
 3. A lens material as claimed in claim 1, wherein said color filter regions are hexagonal and are arranged so that no two regions of the same color are adjacent.
 4. A spectacle lens for a person with deficient color vision, said lens comprising a support, and a lens material on said support comprising a transparent mosaic including a plurality of juxtaposed small color filter regiOns of different colors adapted to compensate for the deficient color vision of the wearer, said regions being arranged in repeating groups to provide a substantially uniform distribution of said filter regions throughout said mosaic, said color filter regions having respective spectral transmission factors which differ in magnitude in inverse proportion to the diagnosed sensitivity of the intended user to the primary colors, red, green and blue.
 5. A spectacle lens as claimed in claim 4, wherein said support is a clear lens element and said mosaic is a photographic diapositive mounted on said lens element on the side thereof closes to the wearer.
 6. A spectacle lens as claimed in claim 4, wherein said support is a clear lens element and said mosaic is a photographic composition on said lens element. 